Catalyst composition and process for producing copolymer

ABSTRACT

A method for block copolymerization of a conjugated diene and an aromatic vinyl compound, which comprises the steps of carrying out homopolymerization of the conjugated diene in the presence of a catalyst composition comprising the following components: (A) a metallocene type complex of a rare earth metal compound, and (B) an ionic compound composed of a non-coordinate anion and a cation and/or an aluminoxane, and then adding the aromatic vinyl compound, and a catalyst composition for polymerization of a conjugated diene or copolymerization of a conjugated diene and an aromatic vinyl compound, which comprises the following components: (D) a neodymium complex, and (B) an ionic compound composed of a non-coordinate anion and a cation and/or an aluminoxane.

TECHNICAL FIELD

The present invention relates to a method for preparing a blockcopolymer of a conjugated diene and an aromatic vinyl compound and aspecific block copolymer prepared by the method.

The present invention also relates to a catalyst composition forpolymerization of a conjugated diene and a co-catalyst contained in thecatalyst composition, as well as a method for preparing a polymer of aconjugated diene using the catalyst composition and a novel conjugateddiene polymer obtainable by the preparation method.

The present invention further relates a catalyst composition forcopolymerization of a conjugated diene and an aromatic vinyl compoundand a co-catalyst contained in the catalyst composition, as well as amethod for preparing a copolymer of a conjugated diene and an aromaticvinyl compound using the catalyst composition and a novel copolymerobtainable by the preparation method.

BACKGROUND ART

Various proposals have been made so far with regard to polymerizationcatalysts for conjugated dienes and aromatic vinyl compounds, and theyplay a highly important role in industrial fields. In particular, inorder to obtain block copolymers of a conjugated diene and an aromaticvinyl compound with enhanced performance in thermal and mechanicalproperties, living anionic polymerization utilizing an alkyllithium as apolymerization initiator has been studied and developed.

In the living anionic polymerization, copolymers with different chemicalstructures having variety of characteristics can be prepared by suitablychoosing various polymerization conditions such as addition amounts ofthe polymerization initiator, amounts and addition time of monomers. Theliving anionic polymerization is a reaction that is not accompanied bydeactivation or novel production of reactive ends by the chain transferreaction during polymerization, as compared to the radicalpolymerization, and the reaction is known to have a feature thatmolecular weight distribution of the resulting polymer is extremelynarrower than that of a polymer obtained by the radical polymerization.However, in a polymerization system using an alkyllithium, it isdifficult to control stereoregularity of conjugated diene moieties of acopolymer so as to give 1,4-cis-linkages.

Various copolymerization catalysts giving high stereoregularity with1,4-cis-linkages for conjugated diene segments have been studied anddeveloped so far. For example, complex catalyst systems are known whichcontain a compound of transition metal such as nickel, cobalt andtitanium as a main component (see, Kogyo Kagaku Zasshi (Journal ofIndustrial Chemistry), 72, 2081, 1969; Plast. Kautsch., 40, 356, 1993;Makromol. Chem. Phys., 195, 2623, 199 etc.), and which contain acompound of rare earth metal such as neodymium and gadolinium as a maincomponent (Macromol. Rapid Commun. 16, 563, 1992; J. Polym. Sci., ParA;Polym. Chem., 32, 1195, 1994; Polymer, 37, 349, 1996) and the like.Although these catalyst systems exhibit a relatively highcis-1,4-controllability, polymers with a high molecular weight andnarrow molecular weight distribution, and copolymers with randomizedmonomer sequence cannot be obtained by means of these catalysts.Further, the polymerization of dienes does not proceed in the manner ofliving polymerization, and it is extremely difficult to introduce anaromatic vinyl compound to a polymerization terminus.

In order to attain a higher cis-1,4-linkage content and superiorpolymerization activity, complex catalyst systems which consist of arare earth metal compound and an organometallic compound belonging toGroup I to Group III have been studied and developed, and highlystereospecific polymerization has come to be actively studied (see,Makromol. Chem. Suppl, 4, 61, 1981; J. Polym. Sci., Polym. Chem. Ed.,18, 3345, 1980; German Patent Application No. 2,848,964; Sci. Sinica.,2/3, 734, 1980; Rubber Chem. Technol., 58, 117, 1985 and the like).Among these catalyst systems, complex catalysts containing a neodymiumcompound and an organoaluminum compound as main components were revealedto give a high cis-1,4-linkage content and have superior polymerizationactivity. The catalysts have already been used in industrialapplications as polymerization catalysts for butadiene and the like(see, Macromolecules, 15, 230, 1982; Makromol. Chem., 94, 119, 1981).

With the recent progress of industrial technologies, requirements forpolymeric materials as commercial products have become increasinglyhigher, and development of polymeric materials which have still higherthermal properties (thermal stability and the like) and mechanicalproperties (tensile modulus, bending modulus and the like) has come tobe strongly desired. As one of promising means for achieving the object,attempts have been made to produce a polymer of a highcis-1,4-configuration content in microstructure and a narrow molecularweight distribution by using a catalyst having a high polymerizationactivity for conjugated dienes. However, no method has so far been foundfor producing polymers having such characteristics.

DISCLOSURE OF THE INVENTION

The first object of the present invention is to provide a method forpreparing a block copolymer of a conjugated diene and an aromatic vinylcompound. More specifically, the object is to provide a method forpreparing a block copolymer with high cis-1,4-configuration content inthe microstructure, a high molecular weight, and a narrow molecularweight distribution. Another object of the present invention is toprovide a copolymer having the aforementioned characteristics.

The second object of the present invention is to provide a catalyst forthe polymerization of a conjugated diene. More specifically, the objectis to provide a catalyst for polymerization for producing a polymer witha high cis-1,4-configuration content in the microstructure and a narrowmolecular weight distribution. Another object of the present inventionis to provide a polymer having the aforementioned characteristics, and amethod for producing the same.

Further object of the present invention is to provide a catalyst forcopolymerization of a conjugated diene and an aromatic vinyl compound.More specifically, the object is to provide a catalyst forpolymerization for producing a copolymer with a highcis-1,4-configuration content in the microstructure, a high molecularweight, and a narrow molecular weight distribution, preferably a blockcopolymer having such characteristics. Another object of the presentinvention is to provide a copolymer having the aforementionedcharacteristics, and a method for producing the same.

The inventors of the present invention conducted various studies inorder to achieve the aforementioned first object. As a result, theinventors of the present invention found that a conjugated diene and anaromatic vinyl compound can be efficiently copolymerized into a blockcopolymer by using a catalyst composition comprising a rare earth metalmetallocene-type polymerization catalyst and a co-catalyst containing anionic compound composed of a non-coordinate anion and a cation and/or analuminoxane in combination. They also found that, by using theaforementioned catalyst composition for copolymerization, a conjugateddiene and an aromatic vinyl compound can be copolymerized to prepare acopolymer with an extremely high cis-1,4-configuration content in themicrostructure as well as a high molecular weight and a narrow molecularweight distribution.

The inventors of the present invention also conducted various studies inorder to achieve the aforementioned second object. As a result, theyfound that conjugated dienes can be efficiently polymerized by using acatalyst composition comprising a rare earth metal metallocene typepolymerization catalyst such as samarium complexes and a co-catalystcomprising an ionic compound composed of a non-coordinate anion and acation and/or an aluminoxane in combination, and that a conjugated dienepolymer with an extremely high cis-1,4-configuration content in themicrostructure and a narrow molecular weight distribution can beproduced by using the aforementioned catalyst composition forpolymerization. Further, they found that this method can also be usedfor preparation of copolymers (PCT/JP00/1188). The inventors of thepresent invention further conducted studies and found that neodymiumcomplexes among rare earth metal metallocene type polymerizationcatalysts gave particularly superior polymerization activity. Thepresent invention was achieved on the basis of these findings.

The present invention thus provides a method for block copolymerizationof a conjugated diene and an aromatic vinyl compound, which comprisesthe steps of carrying out homopolymerization of a conjugated diene inthe presence of a catalyst composition comprising the followingcomponents:

-   (A) a metallocene type complex of a rare earth metal compound, and-   (B) an ionic compound composed of a non-coordinate anion and a    cation and/or an aluminoxane,    and then adding the aromatic vinyl compound.

According to preferred embodiments of the present invention, there areprovided the aforementioned method, wherein the metallocene type complexis a samarium complex; the aforementioned method, wherein the ioniccompound is triphenylcarbonium tetrakis(pentafluorophenyl)borate,triphenylcarbonium tetrakis(tetrafluorophenyl)borate,N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate or1,1′-dimethylferrocenium tetrakis(pentafluorophenyl)borate; and theaforementioned method, wherein the catalyst composition further containsan organometallic compound of an element belonging to from Group I toGroup III in the periodic table.

According to another aspect of the present invention, there is provideda block copolymer, which is obtainable by block copolymerization of aconjugated diene and an aromatic vinyl compound in the presence of theaforementioned catalyst composition for polymerization. In addition,there is also provided a block copolymer, wherein acis-1,4-configuration content in the microstructure is 80 mol % or more,preferably 90 mol % or more, and most preferably 95 mol % or more, amolecular weight Mn is 10,000 or more, preferably 20,000 or more, morepreferably 50,000 or more, and most preferably 100,000 or more, and amolecular weight distribution Mw/Mn is 2.50 or less, preferably 2.00 orless, more preferably 1.80 or less, and most preferably 1.50 or less.This copolymer can be produced by block copolymerization of a conjugateddiene and an aromatic vinyl compound according to the aforementionedmethod.

According to a further aspect of the present invention, there isprovided a catalyst composition for polymerization of a conjugated dieneor copolymerization of a conjugated diene and an aromatic vinylcompound, which contains the following components: (D) a neodymiumcomplex, and (B) an ionic compound composed of a non-coordinate anionand a cation and/or an aluminoxane. According to preferred embodimentsof the present invention, there are provided the aforementioned catalystcomposition, wherein the ionic compound is triphenylcarboniumtetrakis(pentafluorophenyl)borate, triphenylcarboniumtetrakis(tetrafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate or 1,1′-dimethylferroceniumtetrakis(pentafluorophenyl)borate; and the aforementioned catalystcomposition, which further contains an organometallic compound of anelement belonging to from Group I to Group III in the periodic table.

According to a further aspect of the present invention, there isprovided a co-catalyst for use in combination with a catalyst containinga neodymium complex for polymerization of a conjugated diene or acatalyst containing a neodymium complex for copolymerization of aconjugated diene and an aromatic vinyl compound, which comprises anionic compound composed of a non-coordinate anion and a cation and/or analuminoxane. According to further aspects of the present invention,there are provided a method for polymerization of a conjugated diene,wherein the polymerization is carried out in the presence of theaforementioned catalyst composition for polymerization; and a method forcopolymerization of a conjugated diene and an aromatic vinyl compound,wherein the copolymerization is carried out in the presence of theaforementioned catalyst composition for polymerization.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 depicts ¹H NMR spectrum of the block copolymer obtained inExample 2.

FIG. 2 depicts ¹³C NMR spectrum of the block copolymer obtained inExample 2.

FIG. 3 depicts GPC chart of the block copolymer obtained in Example 2.

BEST MODE FOR CARRYING OUT THE INVENTION

Examples of the metallocene type complex of a rare earth metal compoundinclude divalent or trivalent rare earth metal compounds represented bythe general formula (I): R_(a)MX_(b)·L_(c) or the general formula (II):R_(a)MX_(b)QX_(b) wherein M represents a rare earth metal; R representscyclopentadienyl group, a substituted cyclopentadienyl group, indenylgroup, a substituted indenyl group, fluorenyl group, or a substitutedfluorenyl group; X represents hydrogen atom, a halogen atom, an alkoxidegroup, a thiolate group, an amido group, or a hydrocarbon group having 1to 20 carbon atoms; L represents a Lewis base compound; Q represents anelement belonging to Group III in the periodic table; symbol “a”represents an integer of 1, 2 or 3; “b” represents an integer of 0, 1 or2; and “c” represents an integer of 0, 1 or 2.

In the aforementioned general formula (I), an element selected fromthose of atomic numbers 57 to 71 in the periodic table can be used asthe rare earth metal represented by M. Specific examples of the rareearth metal include lanthanium, cerium, praseodymium, neodymium,promethium, samarium, europium, gadolinium, terbium, dysprosium,holmium, erbium, thulium, ytterbium and lutetium. Among them, samariumis preferred. When the symbol “a” is 2, two of “R” may be the same ordifferent from each other. Similarly, when the symbol “b” or “c” is 2,two of “X” or “L” may be the same or different from each other.

The types, numbers, and substituting positions of one or moresubstituents of the substituted cyclopentadienyl group, substitutedindenyl group, and substituted fluorenyl group are not particularlylimited. Examples of the substituent include, for example, methyl group,ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutylgroup, sec-butyl group, tert-butyl group, hexyl group, phenyl group andbenzyl group, as well as hydrocarbon groups containing a silicon atomsuch as trimethylsilyl group. R may be bound to a part of X by means ofa bridging group such as dimethylsilyl group, dimethylmethylene group,methylphenylmethylene group, diphenylmethylene group, ethylene group,and substituted ethylene group, and two of R may be bound to each otherby means of a bridging group such as dimethylsilyl group,dimethylmethylene group, methylphenylmethylene group, diphenylmethylenegroup, ethylene group, and substituted ethylene group.

Specific examples of the substituted cyclopentadienyl group include, forexample, methylcyclopentadienyl group, benzylcyclopentadienyl group,vinylcyclopentadienyl group, 2-methoxyethylcyclopentadienyl group,trimethylsilylcyclopentadienyl group, tert-butylcyclopentadienyl group,ethylcyclopentadienyl group, phenylcyclopentadienyl group,1,2-dimethylcyclopentadienyl group, 1,3-dimethylcyclopentadienyl group,1,3-di(tert-butyl)cyclopentadienyl group,1,2,3-trimethylcyclopentadienyl group,1,2,3,4-tetramethylcyclopentadienyl group, pentamethylcyclopentadienylgroup, 1-ethyl-2,3,4,5-tetramethylcyclopentadienyl group,1-benzyl-2,3,4,5-tetramethylcyclopentadienyl group,1-phenyl-2,3,4,5-tetramethylcyclopentadienyl group,1-trimethylsilyl-2,3,4,5-tetramethylcyclopentadienyl group,1-trifluoromethyl-2,3,4,5-tetramethylcyclopentadienyl group and thelike. Specific examples of the substituted indenyl group include, forexample, 1,2,3-trimethylindenyl group, heptamethylindenyl group,1,2,4,5,6,7-hexamethylindenyl group and the like.Pentamethylcyclopentadienyl group is preferred as R.

The alkoxide group represented by X may be any of aliphatic alkoxygroups such as methoxy group, ethoxy group, propoxy group, n-butoxygroup, isobutoxy group, sec-butoxy group and tert-butoxy group, and aryloxide groups such as phenoxy group, 2,6-di-tert-butylphenoxy group,2,6-diisopropylphenoxy group, 2,6-dineopentylphenoxy group,2-tert-butyl-6-isopropylphenoxy group, 2-tert-butyl-6-neopentylphenoxygroup and 2-isopropyl-6-neopentylphenoxy group. Preferred is2,6-di-tert-butylphenoxy group.

The thiolate group represented by X may be any of aliphatic thiolategroups such as thiomethoxy group, thioethoxy group, thiopropoxy group,thio-n-butoxy group, thioisobutoxy group, thio-sec-butoxy group,thio-tert-butoxy group, and aryl thiolate groups such as thiophenoxygroup, 2,6-di-tert-butylthiophenoxy group, 2,6-diisopropylthiophenoxygroup, 2,6-dineopentylthiophenoxy group,2-tert-butyl-6-isopropylthiophenoxy group,2-tert-butyl-6-thioneopentylphenoxy group,2-isopropyl-6-thioneopentylphenoxy group and2,4,6-triisopropylthiophenoxy group. Preferred is2,4,6-triisopropylthiophenoxy group.

The amido group may be any of aliphatic amido groups such asdimethylamido group, diethylamido group and diisopropylamido group, andarylamido groups such as phenylamido group, 2,6-di-tert-butylphenylamidogroup, 2,6-diisopropylphenylamido group, 2,6-dineopentylphenylamidogroup, 2-tert-butyl-6-isopropylphenylamido group,2-tert-butyl-6-neopentylphenylamido group,2-isopropyl-6-neopentylphenylamido group and 2,4,6-tert-butylphenylamidogroup. Preferred is 2,4,6-tert-butylphenylamido group.

The halogen atom represented by X may be any of fluorine atom, chlorineatom, bromine atom, and iodine atom. Chlorine atom and iodine atom arepreferred. Specific examples of the hydrocarbon group having 1 to 20 ofcarbon atoms include, for example, linear or branched aliphatichydrocarbon groups such as methyl group, ethyl group, n-propyl group,isopropyl group, n-butyl group, isobutyl group, sec-butyl group,tert-butyl group, neopentyl group, hexyl group and octyl group, aromatichydrocarbon groups such as phenyl group, tolyl group and naphthyl group,and aralkyl groups such as benzyl group, as well as hydrocarbon groupscontaining a silicon atom such as trimethylsilylmethyl group andbistrimethylsilylmethyl group. Among them, methyl group, ethyl group,isobutyl group, trimethylsilylmethyl group and the like are preferred.As X, hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to20 carbon atoms is preferred.

The Lewis base compound represented by L is not particularly limited solong as said compound can coordinate to a metal by means of an electronpair, and the compound may be an inorganic compound or an organiccompound. Examples of the Lewis base compound include ether compounds,ester compounds, ketone compounds, amine compounds, phosphine compounds,silyloxy compounds and the like. However, the compounds are not limitedto the above examples. In the general formula (II), Q represents anelement belonging to Group III in the periodic table. Examples of suchan element are-boron, aluminum, gallium and the like. Aluminum ispreferred.

Specific examples of the metallocene type complex of a rare earth metalcompound represented by the formula (I) include, for example,bispentamethylcyclopentadienylbistetrahydrofuran samarium,methylbispentamethylcyclopentadienyltetrahydrofuran samarium,chlorobispentamethylcyclopentadienyltetrahydrofuran samarium,iodobispentamethylcyclopentadienyltetrahydrofuran samarium and the like.Examples of the metallocene type complex of a rare earth metal compoundrepresented by the formula (II) include, for example,dimethylaluminum(μ-dimethyl)-bis(pentamethylcyclopentadienyl) samariumand the like.

The ionic compound used as a co-catalyst is not particularly limited solong as the compound is composed of a non-coordinate anion and a cation.Examples include, for example, ionic compounds that can react with theaforementioned rare earth metal compounds to generate a cationictransition metal compound. Examples of the non-coordinate anion include,for example, tetra(phenyl)borate, tetrakis(monofluorophenyl)borate,tetrakis(difluorophenyl)borate, tetrakis(trifluorophenyl)borate,tetrakis(trifluorophenyl)borate, tetrakis(pentafluorophenyl)borate,tetrakis(tetrafluoromethylphenyl)borate, tetra(tolyl)borate,tetra(xylyl)borate, (triphenyl, pentafluorophenyl)borate,[tris(pentafluorophenyl), phenyl]borate,tridecahydride-7,8-dicarbaundecaborate and the like.

Examples of the cation include, for example, carbonium cations, oxoniumcations, ammonium cations, phosphonium cations, cycloheptatrienylcations, ferrocenium cations that contain a transition metal and thelike. Specific examples of the carbonium cations include trisubstitutedcarbonium cations such as triphenylcarbonium cation and trisubstitutedphenylcarbonium cations. Specific examples of the trisubstitutedphenylcarbonium cations include tri(methylphenyl)carbonium cation,tri(dimethylphenyl)carbonium cation and the like. Specific examples ofthe ammonium cations include trialkylammonium cations such astrimethylammonium cation, triethylammonium cation, tripropylammoniumcation, tributylammonium cation and tri(n-butyl)ammonium cation,N,N-dialkylanilinium cations such as N,N-diethylanilinium cation andN,N-2,4,6-pentamethylanilinium cation, dialkylammonium cations such asdi(isopropyl)ammonium cation and dicyclohexylammonium cation and thelike. Specific examples of the phosphonium cations includetriarylphosphonium cations such as triphenylphosphonium cation,tri(methylphenyl)phosphonium cation and tri(dimethylphenyl)phosphoniumcation.

Preferably used ionic compounds are those consisting of a combination ofeach component arbitrarily selected from the non-coordinate anion andthe cation. Preferred examples of the ionic compound are, for example,triphenylcarbonium tetrakis(pentafluorophenyl)borate, triphenylcarboniumtetrakis(tetrafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, 1,1′-dimethylferroceniumtetrakis(pentafluorophenyl)borate and the like. The ionic compounds maybe used alone, or two or more of them may be used in combination. As aLewis acid that can react with a transition metal compound to generate acationic transition metal compound, B(C₆F₅)₃, Al(C₆F₅)₃ and the like maybe used, and these acids may be used in combination with theaforementioned ionic compounds.

As the aluminoxane used as the co-catalyst, for example, those obtainedby contacting an organoaluminum compound with a condensing agent can beused. More specifically, linear aluminoxanes and cyclic aluminoxanesrepresented by the general formula (—Al(R′)O—)_(n) can be used. In theformula, R′ is a hydrocarbon group having 1 to 10 carbon atoms, and thishydrocarbon group may be substituted with a halogen atom and/or analkoxy group. The symbol “n” represents degree of polymerization, and“n” is preferably 5 or more, more preferably 10 or more. Examples of R′include methyl group, ethyl group, propyl group, isobutyl group and thelike, and methyl group is preferred. Examples of the organoaluminumcompound used as a raw material of the aluminoxane include, for example,trialkylaluminum such as trimethylaluminum, triethylaluminum andtriisobutylaluminum, mixtures thereof and the like, andtrimethylaluminum is especially preferred. Aluminoxanes produced byusing a mixture of trimethylaluminum and tributylaluminium as a rawmaterial can also be suitably used. The aluminoxanes may be used incombination with the ionic compounds.

The catalyst composition used for the method of the present inventioncontains the aforementioned components (A) and (B), and may furthercontain an organometallic compound of an element belonging to fromGroups I to III in the periodic table as a component (C). Examples ofthe organometallic compound include organic aluminum compounds, organiclithium compounds, organic magnesium compounds, organic zinc compounds,organic boron compounds and the like. More specifically, methyllithium,butyllithium, phenyllithium, benzyllithium, neopentyllithium,trimethylsilylmethyllithium, bistrimethylsilylmethyllithium,dibutylmagnesium, dihexylmagnesium, diethylzinc, dimethylzinc,trimethylaluminum, triethylaluminum, triisobutylaluminium,trihexylaluminium, trioctylaluminium, tridecylaluminium and the like maybe used. Furthermore, organic metal halide compounds such asethylmagnesium chloride, butylmagnesium chloride, dimethylaluminumchloride, diethylaluminum chloride, sesquiethylaluminum chloride andethylaluminium dichloride, and hydrogenated organometallic compoundssuch as diethylaluminum hydride and sesquiethylaluminum hydride may beused. These organometallic compounds may be used alone, or two or moreof them may be used in combination.

The mixing ratio of the aforementioned components (A) and (B) in theaforementioned composition may be suitably selected depending on thetype of a monomer used for polymerization, the type and conditions of areaction and the like. In a composition containing a rare earth metalcompound and an aluminoxane, the ratio of the component (A) and thecomponent (B) (molar ratio) is generally about 1:1 to 1:10000,preferably 1:10 to 1:1000, and more preferably 1:50 to 1:500. In acomposition containing a rare earth metal compound and an ioniccompound, the ratio of the component (A) and the component (B) (molarratio) may be about 1:0.1 to 1:10, preferably 1:0.2 to 1:5, and morepreferably 1:0.5 to 1:2. In a composition containing the component (C),the mixing ratio of the rare earth metal compound and the component (C)(molar ratio) may be, for example, about 1:0.1 to 1:1000, preferably1:0.2 to 1:500, and more preferably 1:0.5 to 1:50.

The type of the conjugated diene compound as a monomer that can bepolymerized by the polymerization method of the present invention is notparticularly limited. Examples of the monomer include, for example,1,3-butadiene, isoprene, 1,3-pentadiene, 2-ethyl-1,3-butadiene,2,3-dimethylbutadiene, 2-methylpentadiene, 4-methylpentadiene,2,4-hexadiene or the like. Among them, 1,3-butadiene is preferred. Thesemonomer components may be used alone, or two or more of them may be usedin combination.

The type of the aromatic vinyl compound monomer that can becopolymerized by the polymerization method of present invention is notalso particularly limited, and it may be, for example, styrene,p-methylstyrene, m-methylstyrene, p-tert-butylstyrene, α-methylstyrene,chloromethylstyrene, p-tert-butoxystyrene, dimethylaminomethylstyrene,dimethylaminoethylstyrene, vinyltoluene or the like. Among them, styreneis preferred. These monomer components may be used alone, or two or moreof them may be used in combination.

The polymerization method of the present invention may be performedeither in the presence or absence of a solvent. Where a solvent is used,the kind of the solvent is not particularly limited so long as thesolvent is substantially inactive in the polymerization reaction and hassufficient solubility for the monomer and the catalyst composition.Examples of the solvent include, for example, saturated aliphatichydrocarbons such as butane, pentane, hexane and heptane; saturatedcycloaliphatic hydrocarbons such as cyclopentane and cyclohexane;monoolefins such as 1-butene and 2-butene; aromatic hydrocarbons such asbenzene and toluene; halogenated hydrocarbons such as methylenechloride, chloroform, carbon tetrachloride, trichloroethylene,perchloroethylene, 1,2-dichloroethane, chlorobenzene, bromobenzene andchlorotoluene. Among them, toluene is preferred. Two or more solventsmay be used in combination.

Polymerization temperature in the polymerization method of the presentinvention may be, for example, in the range of from −100° C. to 100° C.,preferably in the range of from −50° C. to 80° C. Polymerization timemay be, for example, about 1 minute to 50 hours, preferably about 5minutes to 5 hours. However, these reaction conditions may be suitablyselected depending on the type of monomers and the type of the catalystcomposition, and they are not limited to the ranges exemplified above.After homopolymerization of conjugated diene is carried out and thepolymerization degree reaches a given level, an aromatic vinyl compoundcan be added and polymerization reaction can be further carried outuntil the polymerization degree reaches a given level. After thepolymerization degree reaches the given level, the reaction may bestopped by adding a known polymerization terminator to thepolymerization system, and then a produced copolymer can be separatedfrom the reaction system in a conventional manner.

The content of the cis-configuration in the microstructure of the blockcopolymer of the present invention may generally be 80 mol % or more,preferably 90 mol % or more, and most preferably 95 mol % or more. Themolecular weight Mn may be 10,000 or more, preferably 20,000 or more,more preferably 50,000 or more, and most preferably 100,000 or more, andthe molecular weight distribution Mw/Mn may be 2.50 or less, preferably2.00 or less, more preferably 1.80 or less, and most preferably 1.50 orless. The copolymer of the present invention is a block copolymer thathas a sequence substantially consisting of blocks of the same monomers.The copolymers of present invention are expected to have superiorthermal characteristics (thermal stability and the like) and mechanicalproperties (tensile modulus, bending modulus, impact resistance and thelike), and therefore, they can be utilized for various applications aspolymeric materials.

Examples of the neodymium complex contained in the catalyst compositionprovided as the second aspect of the present invention include trivalentneodymium complexes represented by the general formula (II):R_(a)MX_(b)·L_(c) or the general formula (IV): R_(a)MX_(b)QX_(b) whereinM represents neodymium; R represents pentadienyl group, a substitutedpentadienyl group, cyclopentadienyl group, a substitutedcyclopentadienyl group, indenyl group, a substituted indenyl group,fluorenyl group, or a substituted fluorenyl group; X represents hydrogenatom, a halogen atom, an alkoxide group, a thiolate group, an amidogroup, or a hydrocarbon group having 1 to 20 carbon atoms; L representsa Lewis base compound; Q represents an element belonging to Group III inthe periodic table; “a” represents an integer of 1, 2, or 3; “b”represents an integer of 0, 1 or 2; and “c” represents an integer of 0,1 or 2. When the symbol “a” is 2, two of “R” may be the same ordifferent from each other. Similarly, when the symbol “b” or “c” is 2,two of a “X” or “L” may be the same or different from each other.

As the substituted pentadienyl group, substituted cyclopentadienylgroup, substituted indenyl group and substituted fluorenyl grouprepresented by R; the alkoxide group, thiolate group, amido group,halogen atom and hydrocarbon group having 1 to 20 carbon atomsrepresented by X, the Lewis base compound represented by L, and elementbelonging to Group III in the periodic table represented by Q, thoseexplained above can be used.

Specific examples of the neodymium complex represented by the generalformula (III) include, for example, tris(2,4-dimethylpentadienyl)neodymium, chlorobis(2,4-dimethylpentadienyl) neodymium,dichloro(2,4-dimethylpentadienyl) neodymium,methylbispentamethylcylcopentadienyltetrahydrofuran neodymium,chlorobispentamethylcylcopentadienyltetrahydrofuran neodymium,iodobispentamethylcyclopentadienyltetrahydrofuran neodymium and thelike. Specific examples of the neodymium complex represented by thegeneral formula (IV) include, for example,dimethylaluminium(μ-dimethyl)bis-(pentamethylcyclopentadienyl) neodymiumand the like.

As the ionic compound and/or aluminoxane used as the co-catalyst, thoseexplained above can be used. The catalyst composition of the presentinvention containing a neodymium complex may contain (C) anorganometallic compound of an element belonging to any of Groups I toIII in the periodic table, besides the aforementioned components (D) and(B). As the organometallic compound, those exemplified above can beused.

The mixing ratio of the aforementioned components (D) and (B) in thecatalyst composition of the present invention containing a neodymiumcomplex may be suitably selected depending on the type of a monomer usedfor polymerization, the type and conditions of a reaction and the like.In a composition containing a neodymium complex and an aluminoxane, theratio of the component (D) and the component (B) (molar ratio) isgenerally about 1:1 to 1:10000, preferably 1:10 to 1:1000, and morepreferably 1:50 to 1:500. In a composition containing a neodymiumcomplex and an ionic compound, the ratio of the component (D) and thecomponent (B) (molar ratio) may be about 1:0.1 to 1:10, preferably 1:0.2to 1:5, and more preferably 1:0.5 to 1:2. In a catalyst compositioncontaining the component (C), the mixing ratio of the neodymium complex(D) and the component (C) (molar ratio) may be, for example, about 1:0.1to 1:1000, preferably 1:0.2 to 1:500, and more preferably 1:0.5 to 1:50.

As conjugated-diene compound monomers that can be polymerized,conjugated-diene compound monomers that can be copolymerized, andaromatic vinyl compound monomers that can be copolymerized in thepolymerization method using the aforementioned catalyst composition ofthe present invention, those monomers exemplified above can be used. Thepolymerization method and polymerization conditions such as temperatureare also similar to those explained above.

The content of the cis-configuration in the microstructure of a polymerthat can be obtained by the method for polymerizing a conjugated dieneusing the catalyst composition of the present invention may generally be80 mol % or more, preferably 90 mol % or more, more preferably 95 mol %or more, and most preferably 98 mol % or more. As for the molecularweight distribution, Mw/Mn may be 2.00 or less, preferably 1.80 or less,more preferably 1.60 or less, further preferably 1.40 or less, and mostpreferably 1.30 or less.

The content of the cis-configuration in the microstructure of thecopolymer that can be obtained by the copolymerization method using thecatalyst composition of the present invention may generally be 80 mol %or more, preferably 90 mol % or more, and particularly preferably 95 mol% or more. The molecular weight Mn may be 10,000 or more, preferably20,000 or more, more preferably 50,000 or more, and most preferably100,000 or more, and the molecular weight distribution Mw/Mn may be 2.50or less, preferably 2.00 or less, more preferably 1.80 or less, and mostpreferably 1.50 or less. The copolymer of the present invention is arandom copolymer that shows a substantially randomized monomer sequence.The copolymers of the present invention are expected to have superiorthermal characteristics (thermal stability and the like) and mechanicalproperties (tensile modulus, bending modulus and the like), andtherefore, they can be utilized for various applications as polymericmaterials.

EXAMPLES

The present invention will be explained more specifically with referenceto the following examples. However, the scope of the present inventionis not limited to these examples. Microstructures of polybutadienereferred to in the examples were calculated from integration ratios ofpeaks observed by ¹H NMR and ¹³C NMR [¹H NMR: δ 4.8-5.0 (=CH₂ of1,2-vinyl unit), 5.2-5.8 (—CH═ of 1,4-unit and —CH═ of 1,2-vinyl unit),¹³C NMR: δ27.4 (1,4-cis unit), 32.7 (1,4-trans unit), 127.7-131.8(1,4-unit), 113.8-114.8 and 143.3-144.7 (1,2-vinyl unit)]. Styrenecontents referred to in the examples were calculated from integrationratios of the peaks obtained by ¹H NMR [δ 4.8-5.0 (═CH₂ of 1,2-vinylunit in butadiene), δ 5.2-5.8 (—CH═ of 1,4-vinyl unit and 1,2-vinyl unitin butadiene) and δ 6.3-7.3 (aromatic ring of styrene unit)]. The weightaverage molecular weights (Mw), number average molecular weights (Mn)and molecular weight distributions (Mw/Mn) were obtained by gelpermeation chromatography (GPC) using polystyrene as a standardsubstance.

Example 1

In a glove box under nitrogen atmosphere, 0.05 mmol ofdimethylaluminum(μ-dimethyl)bis(pentamethylcyclopentadienyl) samarium[(Cp*)₂Sm(μ-Me)₂AlMe₂](Cp*:pentamethylcyclopentadienyl ligand) was putinto a sufficiently dried 30-ml pressure glass bottle and dissolved in 9ml of toluene. Then, 0.15 mmol of triisobutylaluminum and 0.05 mmol oftriphenylcarbonium tetrakis(pentafluorophenyl)borate (Ph₃CB(C₆F₅)₄) wereadded into the bottle, and the bottle was sealed with a stopper. Thebottle was then taken out from the glove box and 0.27 g of 1,3-butadienewas put into the bottle, and polymerization was carried out at −20° C.for 10 minutes. The polymerization product was sampled at this stage,and it was found that the product had a butadiene addition ratio of 98%,weight average molecular weight of 55,400, number average molecularweight of 45,000 and Mw/Mn of 1.23. Then, 0.6 ml of styrene was added tothe bottle, and polymerization was further carried out at −20° C. for 5hours. After the polymerization, 10 ml of methanol containing 10 wt %BHT [2,6-bis(tert-butyl)-4-methylphenol] was added to the reactionsystem to stop the reaction. The polymer was separated by using a largeamount of a mixed solvent of methanol/hydrochloric acid and dried at 60°C. in vacuo. The amount of the resulting polymer was 0.33 g. The styrenecontent in the polymer was 10.0 wt % (5.5 mol %), and the cis-content inthe microstructure of the butadiene units was 99.0 mol %. The weightaverage molecular weight was 60,700, number average molecular weight was46,000, and Mw/Mn was 1.32.

Example 2

In a glove box under nitrogen atmosphere, 0.01 mmol ofdimethylaluminum(μ-dimethyl)bis(pentamethylcyclopentadienyl) samarium[(Cp*)₂Sm(μ-Me)₂AlMe₂] was put into a sufficiently dried 100-ml pressureglass bottle and dissolved in 30 ml of toluene. Then, 0.03 mmol oftriisobutylaluminum and 0.01 mmol of triphenylcarboniumtetrakis(pentafluorophenyl)borate (Ph₃CB(C₆F₅)₄) were added into thebottle, and the bottle was sealed with a stopper. The bottle was thentaken out from the glove box, and 1.70 g of 1,3-butadiene was put intothe bottle. Polymerization was carried out at 50° C. for 10 minutes.Then, 5.0 ml of styrene was added to the bottle, and polymerization wasfurther carried out at 50° C. for 5 hours. After the polymerization, 10ml of methanol containing 10 wt % BHT[2,6-bis(tert-butyl)-4-methylphenol] was added to the reaction system tostop the reaction. The polymer was separated by using a large amount of2-propanol and dried at 60° C. in vacuo. The amount of the resultingpolymer was 1.75 g. The styrene content in the polymer was 10.4 wt %(5.7 mol %), and the cis-content in the microstructure of the butadieneunits was 96.2 mol %. The weight average molecular weight was 801,000,number average molecular weight was 459,400, and Mw/Mn was 1.74.

Example 3

In a glove box under nitrogen atmosphere, 0.01 mmol ofdimethylaluminum(μ-dimethyl)bis(pentamethylcyclopentadienyl) neodymium[(Cp*)₂Nd(μ-Me)₂AlMe₂] was put into a sufficiently dried 30-ml pressureglass bottle and dissolved in 6 ml of toluene. Then, MMAO(toluene-soluble aluminoxane sold by TOSOH and Akzo Co.) was added intothe bottle so that the elemental ratio Al/Nd became 200, and the bottlewas sealed with a stopper. The bottle was then taken out from the glovebox, and 1.5 g of 1,3-butadiene was put into the bottle. Then,polymerization was carried out at 50° C. for 5 minutes. After thepolymerization, 10 ml of methanol containing 10 wt % BHT[2,6-bis(tert-butyl)-4-methylphenol] was added to the reaction system tostop the reaction. The polymer was separated by using a large amount ofa mixed solvent of methanol/hydrochloric acid and dried at 60° C. invacuo. The yield of the resulting polymer was 66 wt %. The cis-contentin the microstructure of the polymer was 97.5 mol %. The number averagemolecular weight was 362,400, and Mw/Mn was 1.89.

Example 4

In a glove box under nitrogen atmosphere, 0.01 mmol ofdimethylaluminum-(μ-dimethyl)bis(pentamethylcyclopentadienyl) neodymium[(Cp*)₂Nd(μ-Me)₂AlMe₂] was put into a sufficiently dried 30-ml pressureglass bottle and dissolved in 6 ml of toluene. Then, 0.03 mmol oftriisobutylaluminum and 0.01 mmol of triphenylcarboniumtetrakis(pentafluorophenyl)borate (Ph₃CB(C₆F₅)₄) were added into thebottle, and the bottle was sealed with a stopper. The bottle was thentaken out from the glove box, and 1.35 g of 1,3-butadiene was put intothe bottle. Polymerization was carried out at 50° C. for 5 minutes.After the polymerization, 10 ml of methanol containing 10 wt % BHT wasadded to the reaction system to stop the reaction. The polymer wasseparated by using a large amount of a mixed solvent ofmethanol/hydrochloric acid and dried at 60° C. in vacuo. The yield ofthe resulting polymer was 76 wt %. The cis-content in the microstructureof the polymer was 96.1 mol %. The number average molecular weight was400,600 and Mw/Mn was 1.66.

Example 5

In a glove box under nitrogen atmosphere, 0.01 mmol ofdimethylaluminum-(μ-dimethyl)bis(pentamethylcyclopentadienyl) neodymium[(Cp*)₂Nd(μ-Me)₂AlMe₂] was put into a sufficiently dried 30-ml pressureglass bottle and dissolved in 6 ml of toluene. Then, 0.03 mmol oftriethylaluminum and 0.01 mmol of triphenylcarboniumtetrakis(pentafluorophenyl)borate (Ph₃CB(C₆F₅)₄) were added into thebottle, and the bottle was sealed with a stopper. The bottle was thentaken out from the glove box, and 1.35 g of 1,3-butadiene was put intothe bottle. Polymerization was carried out at 50° C. for 5 minutes.After the polymerization, 10 ml of methanol containing 10 wt % BHT wasadded to the reaction system to stop the reaction. The polymer wasseparated by using a large amount of a mixed solvent ofmethanol/hydrochloric acid and dried at 60° C. in vacuo. The yield ofthe resulting polymer was 84 wt %. The cis-content in the microstructureof the polymer was 77.0 mol %. The number average molecular weight was239,500, and Mw/Mn was 1.42.

Example 6

In a glove box under nitrogen atmosphere, 0.01 mmol ofdimethylaluminum-(μ-dimethyl)bis(pentamethylcyclopentadienyl) neodymium[(Cp*)₂Nd(μ-Me)₂AlMe₂] was put into a sufficiently dried 30-ml pressureglass bottle and dissolved in 6 ml of toluene. Then, 0.03 mmol oftrimethylaluminum and 0.01 mmol of triphenylcarboniumtetrakis(pentafluorophenyl)borate (Ph₃CB(C₆F₅)₄) were added into thebottle, and the bottle was sealed with a stopper. The bottle was thentaken out from the glove box, and 1.35 g of 1,3-butadiene was put intothe bottle. Then, polymerization was carried out at 50° C. for 5minutes. After the polymerization, 10 ml of methanol containing 10 wt %BHT was added to the reaction system to stop the reaction. The polymerwas separated by using a large amount of a mixed solvent ofmethanol/hydrochloric acid and dried at 60° C. in vacuo. The yield ofthe resulting polymer was 93 wt %. The cis-content in the microstructureof the polymer was 64.8 mol %. The number average molecular weight was353,400, and Mw/Mn was 1.56.

Example 7

In a glove box under nitrogen atmosphere, 0.01 mmol oftris(2,4-dimethyl-pentadienyl) neodymium [(2,4-DMBD)₃Nd] was put into asufficiently dried 30-ml pressure glass bottle and dissolved in 6 ml oftoluene. Then, MMAO (toluene-soluble aluminoxane sold by TOSOH and AkzoCo.) was added into the bottle so that the elemental ratio Al/Nd became200, and the bottle was sealed with a stopper. The bottle was then takenout from the glove box, and 1.35 g of 1,3-butadiene was put into thebottle. Then, polymerization was carried out at 50° C. for 5 minutes.After the polymerization, 10 ml of methanol containing 10 wt % BHT[2,6-bis(tert-butyl)-4-methylphenol] was added to the reaction system tostop the reaction. The polymer was separated by using a large amount ofa mixed solvent of methanol/hydrochloric acid and dried at 60° C. invacuo. The yield of the resulting polymer was 86 wt %. The cis-contentin the microstructure of the polymer was 81.8 mol %. The number averagemolecular weight was 39,700, and Mw/Mn was 2.21.

Example 8

In a glove box under nitrogen atmosphere, 0.03 mmol ofdimethylaluminum-(μ-dimethyl)bis(pentamethylcyclopentadienyl) neodymium[(Cp*)₂Nd(μ-Me)₂AlMe₂] was put into a sufficiently dried 30-ml pressureglass bottle and dissolved in 1 ml of toluene. Then, 0.09 mmol oftriisobutylaluminum and 0.03 mmol of triphenylcarboniumtetrakis(pentafluorophenyl)borate (Ph₃CB(C₆F₅)₄) were added into thebottle, and the bottle was sealed with a stopper. The bottle was thentaken out from the glove box, and 0.81 g of 1,3-butadiene and 1.7 ml ofstyrene were put into the bottle. Then, polymerization was carried outat 50° C. for 1 hour. After the polymerization, 10 ml of methanolcontaining 10 wt % BHT was added to the reaction system to stop thereaction. The polymer was separated by using a large amount of a mixedsolvent of methanol/hydrochloric acid and dried at 60° C. in vacuo. Theyield of the resulting polymer was 25 wt %. The styrene content of thepolymer was 8.1 mol %, and the cis-content in the microstructure of thebutadiene units was 87.8 mol %. The number average molecular weight was46,100, and Mw/Mn was 1.61.

INDUSTRIAL APPLICABILITY

According to the method of the present invention, a block copolymer canbe obtained from a conjugated diene and an aromatic vinyl compound,which has an extremely high content of cis-1,4-configuration in themicrostructure, a high molecular weight and a narrow molecular weightdistribution. Further, when a conjugated diene and an aromatic vinylcompound are copolymerized by using the catalyst composition of presentinvention containing a neodymium complex, a polymer can be obtainedwhich has an extremely high content of cis-1,4-configuration in themicrostructure and a narrow molecular weight distribution.

1. A method for block copolymerization of a conjugated diene and anaromatic vinyl compound, comprising homopolymerizing the conjugateddiene in the presence of a catalyst composition comprising the followingcomponents: (A) a metallocene complex of a rare earth metal compound,and (B) an ionic compound composed of a non-coordinate anion and acation and/or an aluminoxane, before the aromatic vinyl compound isadded.
 2. The method according to claim 1, wherein the metallocenecomplex is a samarium complex.
 3. The method according to claim 1,wherein the ionic compound is triphenylcarboniumtetrakis(pentafluorophenyl)borate, triphenylcarboniumtetrakis(tetrafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate or 1,1′-dimethylferroceniumtetrakis(pentafluorophenyl)borate.
 4. The method according to claim 1,wherein the catalyst composition further comprises an organometalliccompound of an element belonging to Group I to Group III in the periodictable.
 5. A block copolymer, which is obtained by the method accordingto claim
 1. 6. The block copolymer according to claim 5, wherein acis-1,4-configuration content in the microstructure is 80 mol % or more,and a molecular weight distribution Mw/Mn is 2.50 or less.
 7. A blockcopolymer of a conjugated diene and an aromatic vinyl compound, whereina cis-1,4-configuration content in the microstructure is 80 mol % ormore, a molecular weight is 10,000 or more, and a molecular weightdistribution Mw/Mn is 2.50 or less.
 8. A block copolymer according toclaim 7 wherein the cis-1,4-configuration content in the microstructureis 90 mol % or more.
 9. A block copolymer according to claim 7 whereinthe cis-1,4-configuration content in the microstructure is 95 mol % ormore.
 10. A block copolymer according to claim 7 wherein the Mw/Mn is2.00 or less.
 11. A block copolymer according to claim 7 wherein theMw/Mn is 1.80 or less.
 12. A block copolymer according to claim 7wherein the Mw/Mn is 1.50 or less.
 13. A method according to claim 1,wherein the aluminoxane is a linear or cyclic aluminoxane of theformula:—(Al(R′)O—)_(n) where R′ is a hydrocarbon group of 1-10 C atoms and n is5 or more.
 14. A method according to claim 1, wherein the conjugateddiene is 1,3-butadiene, isoprene, 1,3-pentadiene, 2-ethyl-1,3-butadiene,2,3-dimethylbutadiene, 2-methylpentadiene, 4-methylpentadiene, or2,4-hexadiene.
 15. A method according to claim 1, wherein the aromaticvinyl compound is styrene, p-methylstyrene, m-methylstyrene,p-tert-butylstyrene, α-methylstyrene, chloromethyistyrene,p-tert-butoxystyrene, dimethylaminomethylstyrene,dimethylaminoethylstyrene, or vinyltoluene.
 16. The method according toclaim 4, wherein the organometallic compound is an organic aluminumcompound, an organic lithium compound, an organic magnesium compound, anorganic zinc compound, or an organic boron compound.
 17. The methodaccording to claim 4, wherein the organometallic compound ismethyllithium, butyllithium, phenyllithium, benzyllithium,neopentyllithium, trimethylsilylmethyllithium,bistrimetbylsilylmethyllithium, dibutylmagnesium, dihexylmagnesium,diethylzinc, dimethylzinc, trimethylaluminum, triethylaluminum,triisobutylaluxninum, trihexylaluminum, trioctylaluminum,tridecylaluminum, ethylmagnesium chloride, butylmagnesium chloride,dimethylaluminum chloride, diethylaluminum chloride,sesquiethylaluininum chloride, ethylaluminum dichioride,diethylaluininum hydride, sesquiethylaluminuin hydride, or a combinationthereof.